What's a punk?

Mum has started to call me a little punk lately. I don't understand why. Well, actually, I don't even know what it means. So... I googled it. In Wiktionary it says that a punk is:

1. (countable) A person subscribing to the movement, a punk rocker.

   Usage note: An informal plural used within the punk subculture is punx.

2. (countable) A worthless person.

Now, I'm not a punk rocker and I'm DEFINATELY not a worthless person.

I then did an image search to see if that would help... I got this picture....I don't look like this! Sometimes my hair on my head sticks up but usually only when I first wake up or when I've been playing - I don't do it on purpose!

I need some help as to why you think Mum is calling me it. I'll give you an example of how she uses it...
I'll walk up to the car (which I can get into on my own) and put my front feet on the step and turn and smile at Mum - cause if I do that she sometimes helps me up and I don't have to waste precious energy - and she looks at me and calls me a little punk and says that I can do it myself.

So... What's a punk??